Drawing board guides for parallel ruling straightedge

ABSTRACT

On a drawing board having a parallel ruling straightedge with left and right ends and guided at its ends on cables extending from the lower to the upper edges of the board, a first strip of thin flat material at the left end of the board underlying the cable of the left end of the rule and having a vertical wall flange at its left edge for bearing against the left end of the rule. There is also provided a second strip of thin flat material that is parallel to the first strip and which underlies the cable at the right end of the rule as well as the right end of the rule.

United States Patent [191 McNeil DRAWING BOARD GUIDES FOR PARALLEL RULING STRAIGHTEDGE 21 Appl. No.: 430,684

455,154 2/1950 Italy 33/79 Primary ExaminerWilliam D. Martin, .lr. Assistant Examiner-Michael H. Thaler ABSTRACT On a drawing board having a parallel ruling straightedge with left and right ends and guided at its ends on cables extending from the lower to the upper edges of the board, a first strip of thin flat material at the left end of the board underlying the cable of the left end of the rule and having a vertical wall flange at its left edge for bearing against the left end of the rule. There is also provided a second strip of thin flat material that is parallel to the first strip and which underlies the cable at the right end of the rule as well as the right end of the rule.

5 Claims, 3 Drawing Figures US. Patent Oct. 14, 1975 FIG.

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FIG. 3

DRAWING BOARD GUIDES FOR PARALLEL RULING STRAIGIITEDGE BACKGROUND OF THE INVENTION Architects, artists, engineers and draftsmen conventionally use a drawing board that carries a parallel ruling straightedge that is guided on the board by cables. The straightedge rule has pulleys at its left and right ends and the cables ride on the pulleys so that the parallel rule means on the board so that the edge of the rule are maintained parallel regardless of the position of the rule. The cables often ride over the sheet and over a period of time the cables become dirty or soiled and will soil the surface of the paper. Also, the underside of the rule itself will engage the markings on the paper and cause the paper to be soiled. There have been various ways of trying to overcome these problems such as placing cardboard on the surface of the board on which the rule may ride. However, these have not been satisfactory for the reason that the cardboard must be glued or held on the surface by glued paper which in itself creates a condition for picking up soil or dirt.

SUMMARY OF THE INVENTION With the above in mind, it is the primary object of the present invention to provide two strips of hard material that underlie the cables on the board and underlie the ends of the parallel straightedge. The strips may be made of plastic or metal. The strip at the left end has a vertical flange against which the left end of the parallel rule may bear. This will limit the horizontal movement of the parallel edge and consequently retain the cables or ropeson which the parallel rule moves over the respective strips.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front perspective view of a drawing board utilizing the structure of the present invention.

FIG. 2 is a vertical sectional view taken substantially along the line 22 of FIG. 1.

FIG. 3 is a sectional view taken substantially along the line 33 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, a drafting or drawing table has a table base 11 that carries the drawing board 12 on its upper portion so that it may swing vertically in a conventional manner. Braces 13 are provided to hold the drawing board 12 in its inclined position. The braces may be located in different positions so as to adjust the angle of the board. The drawing board 12 has a front edge 14, and a rear edge 15. Carried on the drawing board 12 is a conventional-type parallel rule 17 that has a left end and a right end that extends substantially the width of the board 12. Adjacent the left end of the board 12 is a fiber cable or rope l8, and adjacent the right end of the board 12 is a fiber cable or rope 19. The parallel rule 17 carries at its left and right ends suitable pulleys, not shown, that engage the cables 18, I9 so that the entire rule 17 may be moved to various parallel positions. This is a conventional-type parallel rule and the cables 18, 19 on which the rule is guided is also conventional. Therefore, the rule 17 and its cables 18, 19 are not meant to be a part of the invention but rather to serve as an environment in which the present invention can best be utilized.

The board 12 has a left edge 20 and a right edge 21. Fixed to the surface of the board adjacent the left edge 20 is a guide 25 for the left end of the rule 17. The guide 25 is composed of a lower horizontal plastic strip 27 and an integral vertical flange 28. As can best be seen in FIG. 2, the cable 18 as well as the left end of the parallel rule 17 is carried on the guide 25 with the cable 18 lying substantially at the corner of the strip 17 and the flange 28.

Carried on the right end of the board 12 is a second strip 26. This lies under the right end of the parallel rule 17 and also under the cable or rope 19 on the right end of the board 12. The guides 25, 26 are mounted on the board 12 by means of screws 30, 31, 32 and 33 that penetrate through the strips 27, 26 and into the board 12. The lower ends of the strips 27, 26 are provided with elongated slots 36 through which the respective screws 30, 32 extend. In many instances, it will be desired to slide paper under the guides 25, 26 and consequently it may be necessary to slightly raise the strip 27, 26. For this reason, the slots 36, 37 are provided in the lower ends so as to permit a small takeup in the center of the strips 27, 26 so that paper may be slid under the strips. For purposes of neatness, a small countersunk washer 38 is provided for each of the screws 30-33.

Referring to FIG. 1, when a paper 34 is provided on the surface of the board 12, it is desirable to have the undersurface of the rule 17 placed spacedly above the surface of the paper. The two strips 27, 26 therefore must be of sufficient thickness to raise the center of the rule 17 above the surface of the paper. For this reason, it is recommended that the thickness of the strips 27, 26 be the range 0.035 to 0.070. This will provide sufficient spacing between the rule and board while retaining the accuracy needed for using an edge of the rule 17 to mark a line on the board. The guides 25, 26 may of plastic or metal material, depending on what is available, and it is anticipated that either would work satisfactorily.

As may be seen from FIG. 1, the guides for a rule will provide a board with a neat professional appearance and will provide long-lasting and smooth even surfaces for both edges of the parallel rule. By limiting the horizontal movement of the rule 17 as it bears against the flange 28, it will normally retain the cables for ropes 18, 19 above the guies 25, 26. Thus, the cables or guides should never be over the paper where they could soil the paper. The vertical projection 28 as well as the edges of the strips 27, 26 may be used to provide vertical straightedges for marking the paper. As mentioned previously, the guides 25, 26 due to their relatively thin gauge are sufficiently flexible to permit paper to slide under the strips. By providing means of holding the rule 17 above the surface of the paper, it will generally eliminate feathering when working with ink on the drawings. The guides 25, 26 may be reversed without problem depending on where it is desirable to have the vertical flange 28. Also, while is has been shown to use screws 30-33 for holding the strips on the board, other things may be used such as, for example, thumb tacks.

I claim:

1. On a drawing board having a parallel rule with left and right ends and guided at the ends on cables extending in directions substantially perpendicular to the rule, said cables extending from the lower to the upper edges of the board, the improvement comprising: a first strip of a thin plastic layer of material fixed only at its upper and lower ends to the board adjacent an edge of the board and underlying an end of the parallel rule and the respective cable at the end; a second strip of thin plastic material fixed only at its upper and lower ends to the board adjacent its opposite edge and underlying the opposite end of the parallel rule and the respective cable at that end, at least one of said strips having a vertical flange for engaging the respective end of the rule so as to limit the horizontal movement of the rule in one direction.

2 The invention as set forth in claim 1 in which the respective strips are fixed at their upper and lower ends to the drawing board and said strips are flexible so as to permit drawing paper to slide thereunder.

3. On a drawing board having a parallel edge rule with left and right ends and guided at its ends on cables extending from the lower to the upper edges of the board, the improvement comprising: a first strip of thin flat material at the left end of the board and underlying the cable at the left end, said strip having a vertical wall at its left edge for bearing against the left end of the rule; a second strip of thin flat material parallel to the first and underlying the cable at the right end and the right end of the rule; and means fixing the strips to the drawing board at their respective ends, said strips being flexible so that paper may slide thereunder.

4. The invention defined in claim 3 in which the strips are between 0.035 and 0.070 in thickness.

5. The invention defined in claim 3 in which the means fixing the strips to the drawing board are members that extend through openings in the strips and into the drawing board, and at least one of the openings for each strip is elongated lengthwise of the strip to permit raising of the respective strips so as to permit paper to slide thereunder. 

1. On a drawing board having a parallel rule with left and right ends and guided at the ends on cables extending in directions substantially perpendicular to the rule, said cables extending from the lower to the upper edges of the board, the improvement comprising: a first strip of a thin plastic layer of material fixed only at its upper and lower ends to the board adjacent an edge of the board and underlying an end of the parallel rule and the respective cable at the end; a second strip of thin plastic material fixed only at its upper and lower ends to the board adjacent its opposite edge and underlying the opposite end of the parallel rule and the respective cable at that end, at least one of said strips having a vertical flange for engaging the respective end of the rule so as to limit the horizontal movement of the rule in one direction.
 2. The invention as set forth in claim 1 in which the respective strips are fixed at their upper and lower ends to the drawing board and said strips are flexible so as to permit drawing paper to slide thereunder.
 3. On a drawing board having a parallel edge rule with left and right ends and guided at its ends on cables extending from the lower to the upper edges of the board, the improvement comprising: a first strip of thin flat material at the left end of the board and underlying the cable at the left end, said strip having a vertical wall at its left edge for bearing against the left end of the rule; a second strip of thin flat material parallel to the first and underlying the cable at the right end and the right end of the rule; and means fixing the strips to the drawing board at their respective ends, said strips being flexible so that paper may slide thereunder.
 4. The invention defined in claim 3 in which the strips are between 0.035 and 0.070 in thickness.
 5. The invention defined in claim 3 in which the means fixing the strips to the drawing board are members that extend through openings in the strips and into the drawing board, and at least one of the openings for each strip is elongated lengthwise of the strip to permit raising of the respective strips so as to permit paper to slide thereunder. 